This invention relates to aqueous cleaning compositions which contain an organic solvent and are particularly useful in cleaning hard surfaces such as glass, ceramic tile and the like.
Water-based hard surface cleaning compositions are well known, many having been disclosed in the literatures and a number have been sold commercially. Typically, such compositions contain a surfactant, an organic solvent or solvent system and water as well as a variety of other ingredients such as coupling agents, builders, alcohols, ammonia, pH modifiers, germicides, perfumes, opacifiers, dyes, etc. which may be chosen by the skilled formulator to satisfy the""requirements of a particular application.
It is well known that an organic solvent having excellent solvency for soils such as grease and wax needs to be present in water-based cleaning compositions to achieve acceptable results in cleaning hard surfaces such as glass, ceramic tile, etc. An appropriate organic solvent having good cleaning efficiency enhances an aqueous cleaning composition""s ability to remove soils and dirt which may contain organic matter from the hard surface to be cleaned without leaving streaks or residues. However, because of recentregulatory efforts to reduce the presence of volatile organic compounds in products such as cleaning compositions which have significant exposure to the environment, the industry continues to look for more efficient solvent systems which can be used in smaller amounts while maintaining cleaning efficiency. In addition, for commercial acceptance, it is important that the organic solvent does not impart a strong or unpleasant odor to the cleaning composition.
Various glycol ethers, used alone or in combination with other organic solvents, have been recognized as a useful solvent component for aqueous cleaning compositions. For example, ethylene glycol butyl ether has been used as the solvent of choice in numerous commercial cleaning compositions for many years and is disclosed in prior art patents ( see, for example, U.S. Pat. No. 4,983,317). This glycol ether has acceptable cleaning efficiency and good solubility in water-based cleaning compositions. However, its cleaning, efficiency levels off at about 1% by weight in aqueous cleaning composition and, as the data in Table 1 shows, actually declines as more of the solvent is added thus limiting the cleaning efficiency which can be achieved by using this solvent alone.
European Patent Publication 0527625A2 discloses the use of up to about 1.5% ethylene glycol hexyl ether as a solvent in water-based cleaning compositions. This glycol ether has better cleaning efficiency than ethylene glycol butyl ether but is only soluble up to about 1% by weight in the water-based cleaning compositions thus requiring the use of coupling agents and/or cosolvents which may result in the presence of an undesirable level of volatile organics.
U.S. Pat. No. 3,882,038 discloses hard surface cleaning compositions containing certain classes of glycol ether compositions including those represented by the formula:
RO(C2H4O)xcexcH
wherein R is an alkyl group containing from 5 to 8 carbon atoms, and xcexc has a value of from 1 to 6, preferably 1 to 3, with the proviso that xcexc has a value of from 1 to 4 when R contains five carbon atoms, and xcexc has a value of 3 to 6 when R contains from 6 to 8 carbon atoms. This patent discloses a large number of glycol ethers which could be used as a solvent in water-based cleaning compositions including ethylene glycol amyl ether. This amyl ether product is shown by the patentee to have acceptable cleaning efficiency particularly when used with a coupling agent in water-based compositions containing a builder. The ethylene glycol amyl ether disclosed in U.S. Pat. No. 3,882,038 is typically prepared by the reaction of ethylene oxide and amyl alcohol. The xe2x80x9camylxe2x80x9d designation is understood by those knowledgeable in the art to be a mixture of isomers including 40 to 50% or more of the 2-methyl butyl isomer and up to 10% of the 3-methyl butyl isomer in addition to the n-pentyl species. The ethylene glycol amyl ether solvent, while offering an improvement in cleaning efficiency over ethylene glycol butyl ether solvent, has a strong odor and the presence of the 3-methyl butyl isomer creates potential toxicity problems making it unsuitable for commercial use. Thus amyl ether products such as that disclosed in U.S. Pat. No. 3,882,038 have never achieved acceptance in the marketplace for use as a solvent in water-based cleaning compositions.
According to the present invention, applicants have discovered that a specific ethylene glycol pentyl ether product is useful as a solvent component to provide improved water-based cleaning compositions. More specifically, the present invention relates to water-based cleaning compositions which comprise a surfactant, water and an organic solvent component comprising a predominately normal or straight chain ethylene glycol pentyl ether product containing at least about 90% by weight, based on the total weight of the ethylene glycol pentyl ether product of mono-ethylene, diethylene or triethylene glycol n-pentyl ether or mixtures thereof.
The water-based cleaning compositions of the present invention comprise (a) a surfactant component, (b) water and (c) a solvent component comprising an ethylene glycol pentyl ether product which contains at least about 90% by weight of mono-ethylene, diethylene or triethylene glycol n-pentyl ether. Particularly good results are obtained when the ethylene glycol pentyl ether product contains at least about 95% up to 99% or higher by weight of mono-ethylene, diethylene or triethylene glycol n-pentyl ether or mixtures thereof.
The unique properties that this specifically defined ethylene glycol n-pentyl ether product provides when used in water-based cleaning compositions have heretofore gone unrecognized in the art. The water-based cleaning compositions of applicants"" invention exhibit unexpectedly improved cleaning efficiency compared to other glycol ethers while offering other properties necessary for commercial acceptance including acceptable odor characteristics and low toxicity.
In particular, it has been discovered that the water solubility of the ethylene glycol n-pentyl ether product used in the water-based cleaning compositions of the present invention is greater than expected and that suprisingly, its cleaning efficiency continues to increase as its concentration in a water-based cleaning composition increases to the saturation point, thus providing water-based cleaning compositions with cleaning efficiencies significantly superior to any previously known in the art. This effect is not seen with, for example, ethylene glycol butyl ether or ethylene glycol hexyl ether whose cleaning efficiency quickly passes through a maximum and then declines as concentration is increased. This suprising beneficial feature of the ethylene glycol n-pentyl ether solvent of the present invention allows the formulator to tune the cleaning performance of the cleaning compositions of the present invention by changing solvent concentration and to more easily balance cleaning performance with other desirable properties. The presence of higher amounts of the normal pentyl species in the ethylene glycol n-pentyl ether product used in the water-based cleaning compositions of the present invention, in addition to improving cleaning efficiency, results in other benefits such as better odor characteristics, less streaking, better cloud point control and low toxicity.
The ethylene glycol n-pentyl ether product containing at least about 90% by weight of mono-ethylene, diethylene or triethylene glycol n-pentyl ether may be obtained using known, processes and techniques. Such products are advantageously prepared by reacting pentanol containing at least about 90% n-pentanol with ethylene oxide in the presence of a basic or acidic catalyst until a product of the desired molecular weight is obtained. Pentanol containing at least about 90% n-pentanol may be prepared directly utilizing oxo technology disclosed in U.S. Pat. Nos. 3,527,809; 4,283,562; 4,593,011; 4,762,817; 4,769,498; 5,113,022; 5,180,854 and 5,364,950 or by refining a pentanol product containing more than 10% isomers. The ethylene glycol n-pentyl ether product used in the water-based cleaning compositions of the present invention contains minor amounts, i.e. less than 10%, of the 2-methylbutyl isomer but is otherwise essentially free of isomers including highly toxic species such as the 3-methylbutyl species.
The amount of the ethylene glycol n-pentyl ether product used in the water-based cleaning compositions of the present invention will vary depending on the type and amount of other ingredients present. The amount of the ethylene glycol n-pentyl ether used to achieve an optimum balance between cleaning efficiency and other properties such as cloud point while minimizing the overall amount of volatile organic compounds present can readily be determined by the skilled formulator. Typically, the ethylene glycol n-pentyl ether product will be present in an amount of from about 0.05 to about 10.0% by weight, based on the total weight of the cleaning composition. Particularly good results are obtained when the cleaning compositions of the present invention contain up to about 3.0% by weight of the mono-ethylene glycol n-pentyl ether product in alone or in combination with other solvents.
The water-based cleaning compositions of the present invention may contain other organic solvents in addition to the ethylene glycol n-pentyl ether product. Suitable compounds which may be useful as cosolvents are well known and may be selected from alcohols, glycols, glycol ethers, glycol ether esters, ketones, esters, and the like. Examples of such compounds include, without limitation, ethanol, propanol, isopropanol, butanol, glycol, ethylene glycol ethyl ether, ethylene glycol propyl ether, ethylene glycol butyl ether, ethylene glycol hexyl ether, diethylene glycol ethyl ether, diethylene glycol butyl ether, propylene glycol t-butyl ether and mixtures thereof.
Surfactants useful in the cleaning compositions of the present invention are well known and include anionic, nonionic and amphoteric compounds. Examples of such compounds are disclosed in U.S. Pat. Nos. 5,780,482 and 5,437,807 which are incorporated herein by reference. Combinations of more than one such surfactant compound may be used in the cleaning compositions of the present invention. Typically, the total amount of surfactant present in the water-based cleaning compositions of the present invention will be in the range of about 0.01 to about 5.0% by weight, based on the total weight of the composition.
The water-based cleaning compositions of this invention may include any of the well-known and conventional components used in such compositions. Such components include, for example, but without limitation, pH modifying agents, thickenings agents, anti-streaking agents, buffers, builders, chelating or sequestering agents, hydrotopes, anti-microbial agents, colorants, and perfumes. Selection and use of such components is well within the capabilities of the skilled formulator.
The amount of water present in the water-based cleaning compositions of this invention will depend upon the type and amount of other components present. Typically, the amount of water used in such compositions will be in the range of about 50 to about 99% by weight, based on the total weight of the composition. Selection of the appropriate amount of water and the manner in which the various components are combined to prepare the cleaning compositions of this invention are within the skill of a knowledgeable formulator.